you see the brown spots in that is the accumulation of toxic proteins. what can happen is that with repeated injury and over a period of years and years these proteins accumulate and if -- often there's nothing you can do, and they actually can interfere with the way that the brain functions. you can just see it so clearly in those images. >> you know, one of the critical questions a lot of parents obviously have as their kids get involved in sports and progress through, you know, football or hockey or all those sports where you can suffer repeated traumas, what's critical here is that it's not just the concussions that you have to be worried about according to the study, right? >> right. this study -- these folks didn't necessarily have a whole lot of concussions. we're talking about 68 people who they looked at. some of them it was just a matter of, you know, repeated head injuries, you know, and just being sort of batted around over the years. now, it's interesting that the folks in the study were between the ages of 17 and 98, and what they could see